Hearing loss is currently the third most prevalent chronic condition in the elderly with an estimated 25 to 40 percent of the people in this country over the age of 60 suffering from a hearing impairment. In total, approximately 28 million Americans have a hearing impairment. Arguably of greater concern is the fact that hearing loss is on the rise among people of all ages. For example, one National Health survey found that from 1971 to 1990, hearing problems for people between the ages of 45 and 64 have increased by 26 percent while people between the ages of 18 and 44 experienced a 17 percent increase during the same time. In a survey of people in their 50's living in California, researchers found that the rate of impairment jumped 150 percent between 1965 and 1994. A study by the American Medical Association reported that approximately 15 percent of school-aged children have a hearing loss.
Sensorineural hearing loss, which accounts for approximately 90 percent of all hearing loss, can be caused by old age, Menieres disease, ototoxic medications and noise exposure. It is this last cause, noise exposure, which is the likely cause of the current trend of increasing hearing loss. In general, the environment today is much noisier than in the past, the increase due to a variety of sources ranging from machinery (e.g., cars, power tools, lawn mowers, leaf blowers, vacuum cleaners, etc.) to personal entertainment systems (Walkmans, iPods, MP3 players, etc.). Furthermore, these sources of noise are very pervasive, exposing people to high noise levels in the workplace, in recreational settings and at home, providing people with little time to rest their ears.
Noise induced hearing loss (NIHL) is the result of both the sound pressure level (SPL), measured in decibels (dB), and the length of exposure. Accordingly, a person can tolerate a much longer exposure to a lower sound level than to a higher sound level. For example, OSHA (Occupational Safety and Health Administration) estimates that a person can tolerate up to 8 hours per day of a 90 dB sound (e.g., subway train, hair dryer, lawn mower), 2 hours per day of a 100 dB sound source (e.g., chain saw, pneumatic drill), and only a half an hour of a 110 dB sound (e.g., dance club), before experiencing some degree of permanent hearing loss. To make matters worse, except in those cases where a person is exposed to an extremely loud sound such as a gunshot at approximately 165 dB or a firecracker at approximately 180 dB, hearing loss is a very gradual phenomenon in which the effects are cumulative and relatively symptom-less. Accordingly, most people are unaware that they are exposing themselves to ear-damaging sound levels.
It is generally believed that the use of headphones and earbuds has contributed to the rise in hearing loss, especially in younger people. Although in part this may be due to the close proximity of the transducers to the ears, the primary reason appears to be that most users typically listen at very high volume levels. For example, a survey by Australia's National Acoustic Laboratories found that approximately 25 percent of the people that use a portable stereo on a daily basis listen at volume levels high enough to cause hearing loss. Users of headphones and earbuds also appear to be more susceptible to threshold shifting wherein the user adapts to the current volume level and thus increases the volume level to reach the same perceived level, thereby increasing the risk of hearing damage.
Another aspect of typical headphone and earbud use that heightens the risk of hearing loss is that most users turn up the volume in an attempt to drown out background sounds. For example, a recent study found that in a quiet laboratory setting users set their volume level to an average volume of 69 dB, a very safe level. However when the background level was increased to 65 dB, the average volume went up to 82 dB, with some users increasing the volume level to as high as 95 dB. Considering that the noise level generated by city traffic is approximately 80 dB, one may assume that users would turn up the volume on their headsets to an even higher, and more dangerous, level under normal background conditions.
To date, there have been a couple of different approaches taken to lowering the risks of hearing loss when using headphones and earbuds. The first approach is one of public education, both in terms of the risks associated with exposure to loud noises and possible ways of minimizing these risks. The second approach is the use of high quality, in-ear monitors that provide vastly improved ambient noise attenuation, thus allowing the user to listen to their stereo at a safe volume level. Although both approaches are viable, they still require the user to recognize when they are exposing themselves to potentially damaging sound levels. Accordingly, what is needed in the art is an apparatus that visually indicates when the sound level is at a dangerous level. The present invention provides such an apparatus.